/*
Dwarf Therapist
Copyright (c) 2009 Trey Stout (chmod)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#ifndef CP_437_CODEC_H
#define CP_437_CODEC_H

#include <QtCore>

static const char hexchars[] = "0123456789ABCDEF";

// Convert IBM437 character codes 0x00 - 0xFF into Unicode.
static ushort const cp437ToUnicode[256] = {
	0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007,
	0x0008, 0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x000e, 0x000f,
	0x0010, 0x0011, 0x0012, 0x0013, 0x0014, 0x0015, 0x0016, 0x0017,
	0x0018, 0x0019, 0x001c, 0x001b, 0x007f, 0x001d, 0x001e, 0x001f,
	0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,
	0x0028, 0x0029, 0x002a, 0x002b, 0x002c, 0x002d, 0x002e, 0x002f,
	0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,
	0x0038, 0x0039, 0x003a, 0x003b, 0x003c, 0x003d, 0x003e, 0x003f,
	0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
	0x0048, 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f,
	0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,
	0x0058, 0x0059, 0x005a, 0x005b, 0x005c, 0x005d, 0x005e, 0x005f,
	0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,
	0x0068, 0x0069, 0x006a, 0x006b, 0x006c, 0x006d, 0x006e, 0x006f,
	0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,
	0x0078, 0x0079, 0x007a, 0x007b, 0x007c, 0x007d, 0x007e, 0x001a,
	0x00c7, 0x00fc, 0x00e9, 0x00e2, 0x00e4, 0x00e0, 0x00e5, 0x00e7,
	0x00ea, 0x00eb, 0x00e8, 0x00ef, 0x00ee, 0x00ec, 0x00c4, 0x00c5,
	0x00c9, 0x00e6, 0x00c6, 0x00f4, 0x00f6, 0x00f2, 0x00fb, 0x00f9,
	0x00ff, 0x00d6, 0x00dc, 0x00a2, 0x00a3, 0x00a5, 0x20a7, 0x0192,
	0x00e1, 0x00ed, 0x00f3, 0x00fa, 0x00f1, 0x00d1, 0x00aa, 0x00ba,
	0x00bf, 0x2310, 0x00ac, 0x00bd, 0x00bc, 0x00a1, 0x00ab, 0x00bb,
	0x2591, 0x2592, 0x2593, 0x2502, 0x2524, 0x2561, 0x2562, 0x2556,
	0x2555, 0x2563, 0x2551, 0x2557, 0x255d, 0x255c, 0x255b, 0x2510,
	0x2514, 0x2534, 0x252c, 0x251c, 0x2500, 0x253c, 0x255e, 0x255f,
	0x255a, 0x2554, 0x2569, 0x2566, 0x2560, 0x2550, 0x256c, 0x2567,
	0x2568, 0x2564, 0x2565, 0x2559, 0x2558, 0x2552, 0x2553, 0x256b,
	0x256a, 0x2518, 0x250c, 0x2588, 0x2584, 0x258c, 0x2590, 0x2580,
	0x03b1, 0x00df, 0x0393, 0x03c0, 0x03a3, 0x03c3, 0x03bc, 0x03c4,
	0x03a6, 0x0398, 0x03a9, 0x03b4, 0x221e, 0x03c6, 0x03b5, 0x2229,
	0x2261, 0x00b1, 0x2265, 0x2264, 0x2320, 0x2321, 0x00f7, 0x2248,
	0x00b0, 0x2219, 0x00b7, 0x221a, 0x207f, 0x00b2, 0x25a0, 0x00a0
};



// Convert Unicode 0x0000 - 0x00FF into IBM437.
static unsigned char const cp437FromUnicode[256] = {
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
	0x18, 0x19, 0x7f, 0x1b, 0x1a, 0x1d, 0x1e, 0x1f,
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
	0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x1c,
	'?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
	'?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
	'?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
	'?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
	0xff, 0xad, 0x9b, 0x9c, '?' , 0x9d, '?' , 0x15,
	'?' , '?' , 0xa6, 0xae, 0xaa, '?' , '?' , '?' ,
	0xf8, 0xf1, 0xfd, '?' , '?' , '?' , 0x14, 0xfa,
	'?' , '?' , 0xa7, 0xaf, 0xac, 0xab, '?' , 0xa8,
	'?' , '?' , '?' , '?' , 0x8e, 0x8f, 0x92, 0x80,
	'?' , 0x90, '?' , '?' , '?' , '?' , '?' , '?' ,
	'?' , 0xa5, '?' , '?' , '?' , '?' , 0x99, '?' ,
	'?' , '?' , '?' , '?' , 0x9a, '?' , '?' , 0xe1,
	0x85, 0xa0, 0x83, '?' , 0x84, 0x86, 0x91, 0x87,
	0x8a, 0x82, 0x88, 0x89, 0x8d, 0xa1, 0x8c, 0x8b,
	'?' , 0xa4, 0x95, 0xa2, 0x93, '?' , 0x94, 0xf6,
	'?' , 0x97, 0xa3, 0x96, 0x81, '?' , '?' , 0x98
};


class CP437Codec : public QTextCodec {
public:
	CP437Codec(){}
	~CP437Codec(){}

	QByteArray name() const {
		return "IBM437";
	}
	QList<QByteArray> aliases() const {
		QList<QByteArray> retval;
		retval << "cp437" << "437" << "csPC8CodePage437";
		return retval;
	}
	int mibEnum() const {
		return 2011;
	}

protected:
	QString convertToUnicode(const char *in, int length, ConverterState *) const {
		QString str;
		if ( length >= 6 && in[0] == '8' && in[1] == '0' &&
			in[length - 4] == 'F' && in[length - 3] == 'F' &&
			in[length - 2] == 'F' && in[length - 1] == 'F') {

				// UCS-2 string embedded within a 437-encoded string.
				int nibble = 0;
				int value = 0;
				int digit;
				in += 2;
				length -= 6;
				while ( length-- > 0 ) {
					char ch = *in++;
					if ( ch >= '0' && ch <= '9' )
						digit = ch - '0';
					else if ( ch >= 'A' && ch <= 'F' )
						digit = ch - 'A' + 10;
					else if ( ch >= 'a' && ch <= 'f' )
						digit = ch - 'a' + 10;
					else
						continue;
					value = value * 16 + digit;
					++nibble;
					if ( nibble >= 4 ) {
						str += QChar( (ushort)value );
						nibble = 0;
						value = 0;
					}
				}
		} else {
			// Regular 437-encoded string.
			while ( length-- > 0 )
				str += QChar((unsigned int)cp437ToUnicode[*in++ & 0xFF]);
		}
		return str;
	}

	QByteArray convertFromUnicode(const QChar *in, int length, ConverterState *) const {
		QByteArray result;
		unsigned int ch;
		char *out;

        /*
		// Determine if the string should be encoded using the UCS-2 hack.
		bool non437 = false;
		for ( int posn = 0; !non437 && posn < length; ++posn ) {
			ch = in[posn].unicode();
			if ( ch >= 0x0100 )
				non437 = true;
			else if ( cp437FromUnicode[ch] == '?' && ch != '?' )
				non437 = true;
		}
        
		if ( non437 ) {
			// There is a non CP437 character in this string, so use UCS-2.
			result.resize( length * 4 + 6 );
			out = result.data();
			*out++ = '8';
			*out++ = '0';
			while ( length-- > 0 ) {
				uint ch = in->unicode();
				++in;
				*out++ = hexchars[ (ch >> 12) & 0x0F ];
				*out++ = hexchars[ (ch >> 8) & 0x0F ];
				*out++ = hexchars[ (ch >> 4) & 0x0F ];
				*out++ = hexchars[ ch & 0x0F ];
			}
			*out++ = 'F';
			*out++ = 'F';
			*out++ = 'F';
			*out   = 'F';
			return result;
		}*/

		// If we get here, we can guarantee that the string only contains
		// valid CP437 code points between 0x0000 and 0x00FF.
		result.resize(length);
		out = result.data();
		while (length--) {
            ch = in->unicode();
            if (ch >= 0x0100 || ch == '?') {
                *out ++ = '?';
            } else {
			    *out++ = (char)cp437FromUnicode[in->unicode()];
            }
			++in;
		}
		return result;
	}

};



#endif
